The invention relates to a fuel injection nozzle of the type described in the preamble of the main claim. In a conventional fuel injection nozzle of this type, the control slide valve is constructed as a stepped piston and controls, with its rear face, a main feed duct so that the latter is opened, after the preliminary injection stroke has been completed. Apart from the fact that a stepped piston design is expensive with respect to guidance and sealing thereof, it is impossible in such a conventional injection nozzle to obtain a desirable clear separation between preliminary and primary injections and a change in the preliminary injection quantity and preliminary injection period in the assembled condition of the nozzle. Precisely the latter feature is necessary to synchronize the individual engine cylinders with one another, particularly since this synchronization plays an increasingly important role with ever stricter requirements of emission control.